A subvolume is a part of filesystem with its own independent
file/directory hierarchy. Subvolumes can share file extents. A
snapshot is also subvolume, but with a given initial content of the
original subvolume.
Note
A subvolume in btrfs is not like an LVM logical volume, which is
block-level snapshot while btrfs subvolumes are file
extent-based.
A subvolume looks like a normal directory, with some additional
operations described below. Subvolumes can be renamed or moved,
nesting subvolumes is not restricted but has some implications
regarding snapshotting.
A subvolume in btrfs can be accessed in two ways:
· like any other directory that is accessible to the user
· like a separately mounted filesystem (options subvol or subvolid)
In the latter case the parent directory is not visible and
accessible. This is similar to a bind mount, and in fact the
subvolume mount does exactly that.
A freshly created filesystem is also a subvolume, called top-level,
internally has an id 5. This subvolume cannot be removed or replaced
by another subvolume. This is also the subvolume that will be mounted
by default, unless the default subvolume has been changed (see
subcommand set-default).
A snapshot is a subvolume like any other, with given initial content.
By default, snapshots are created read-write. File modifications in a
snapshot do not affect the files in the original subvolume.

create [-i <qgroupid>] [<dest>/]<name>
Create a subvolume <name> in <dest>.
If <dest> is not given, subvolume <name> will be created in the
current directory.
Options
-i <qgroupid>
Add the newly created subvolume to a qgroup. This option can
be given multiple times.
delete [options] <subvolume> [<subvolume>...]
Delete the subvolume(s) from the filesystem.
If <subvolume> is not a subvolume, btrfs returns an error but
continues if there are more arguments to process.
The corresponding directory is removed instantly but the data
blocks are removed later in the background. The command returns
immediately. See btrfs subvolume sync how to wait until the
subvolume gets completely removed.
The deletion does not involve full transaction commit by default
due to performance reasons. As a consequence, the subvolume may
appear again after a crash. Use one of the --commit options to
wait until the operation is safely stored on the device.
Options
-c|--commit-after
wait for transaction commit at the end of the operation.
-C|--commit-each
wait for transaction commit after deleting each subvolume.
-v|--verbose
verbose output of operations.
find-new <subvolume> <last_gen>
List the recently modified files in a subvolume, after <last_gen>
generation.
get-default <path>
Get the default subvolume of the filesystem <path>.
The output format is similar to subvolume list command.
list [options] [-G [+|-]<value>] [-C [+|-]<value>]
[--sort=rootid,gen,ogen,path] <path>
List the subvolumes present in the filesystem <path>.
For every subvolume the following information is shown by
default:
ID <ID> gen <generation> top level <ID> path <path>
where ID is subvolume’s id, gen is an internal counter which is
updated every transaction, top level is the same as parent
subvolume’s id, and path is the relative path of the subvolume to
the top level subvolume. The subvolume’s ID may be used by the
subvolume set-default command, or at mount time via the subvolid=
option.
Options
Path filtering
-o
print only subvolumes below specified <path>.
-a
print all the subvolumes in the filesystem and
distinguish between absolute and relative path with
respect to the given <path>.
Field selection
-p
print the parent ID (parent here means the subvolume
which contains this subvolume).
-c
print the ogeneration of the subvolume, aliases: ogen or
origin generation.
-g
print the generation of the subvolume (default).
-u
print the UUID of the subvolume.
-q
print the parent UUID of the subvolume (parent here means
subvolume of which this subvolume is a snapshot).
-R
print the UUID of the sent subvolume, where the subvolume
is the result of a receive operation.
Type filtering
-s
only snapshot subvolumes in the filesystem will be
listed.
-r
only readonly subvolumes in the filesystem will be
listed.
-d
list deleted subvolumes that are not yet cleaned.
Other
-t
print the result as a table.
Sorting
-G [+|-]<value>
list subvolumes in the filesystem that its generation is
>=, ⟨ or = value. '+' means >= value, '-' means <= value,
If there is neither '+' nor '-', it means = value.
-C [+|-]<value>
list subvolumes in the filesystem that its ogeneration is
>=, <= or = value. The usage is the same to -G option.
--sort=rootid,gen,ogen,path
list subvolumes in order by specified items. you can add
'+' or '-' in front of each items, '+' means ascending,
'-' means descending. The default is ascending.
for --sort you can combine some items together by ',',
just like --sort=+ogen,-gen,path,rootid.
set-default [<subvolume>|<id> <path>]
Set the default subvolume for the (mounted) filesystem.
Set the default subvolume for the (mounted) filesystem at <path>.
This will hide the top-level subvolume (i.e. the one mounted with
subvol=/ or subvolid=5). Takes action on next mount.
There are two ways how to specify the subvolume, by <id> or by
the <subvolume> path. The id can be obtained from btrfs subvolumelist, btrfs subvolume show or btrfs inspect-internal rootid.
show [options] <path>
Show more information about subvolume <path> regarding UUIDs,
times, generations, flags and related snapshots.
/mnt/btrfs/subvolume
Name: subvolume
UUID: 5e076a14-4e42-254d-ac8e-55bebea982d1
Parent UUID: -
Received UUID: -
Creation time: 2018-01-01 12:34:56 +0000
Subvolume ID: 79
Generation: 2844
Gen at creation: 2844
Parent ID: 5
Top level ID: 5
Flags: -
Snapshot(s):
Options
-r|--rootid
rootid of the subvolume.
-u|--uuid
UUID of the subvolume.
snapshot [-r|-i <qgroupid>] <source> <dest>|[<dest>/]<name>
Create a snapshot of the subvolume <source> with the name <name>
in the <dest> directory.
If only <dest> is given, the subvolume will be named the basename
of <source>. If <source> is not a subvolume, btrfs returns an
error.
Options
-r
Make the new snapshot read only.
-i <qgroupid>
Add the newly created subvolume to a qgroup. This option can
be given multiple times.
sync <path> [subvolid...]
Wait until given subvolume(s) are completely removed from the
filesystem after deletion. If no subvolume id is given, wait
until all current deletion requests are completed, but do not
wait for subvolumes deleted in the meantime.
Options
-s <N>
sleep N seconds between checks (default: 1)

This page is part of the btrfs-progs (btrfs filesystem tools)
project. Information about the project can be found at
⟨https://btrfs.wiki.kernel.org/index.php/Btrfs_source_repositories⟩.
If you have a bug report for this manual page, see
⟨https://btrfs.wiki.kernel.org/index.php/Problem_FAQ#How_do_I_report_bugs_and_issues.3F⟩.
This page was obtained from the project's upstream Git repository
⟨git://git.kernel.org/pub/scm/linux/kernel/git/kdave/btrfs-progs.git⟩
on 2019-05-09. (At that time, the date of the most recent commit
that was found in the repository was 2019-02-25.) If you discover
any rendering problems in this HTML version of the page, or you
believe there is a better or more up-to-date source for the page, or
you have corrections or improvements to the information in this
COLOPHON (which is not part of the original manual page), send a mail
to man-pages@man7.org
Btrfs v4.6.1 03/06/2019 BTRFS-SUBVOLUME(8)